For thousands of years, humankind have been fascinated with contests of speed. Initially, foot races were held as a competition to determine the fastest runner. In addition, competitions were held wherein an animals speed was tested, such as horse races, chariot races and the like. With the invention of the automobile, the variety of contests of speed using mechanized transportation has increased. Automobile races take a variety of forms. One such race determines who can travel a given distance in the shortest amount of time.
Automobiles, of course, are known to have an engine which propels drive wheels through a transmission. Typically, transmissions provide a variety of gear ratios to couple the engine's output to the driven wheels in order to provide different torque ratios to the wheels. A driver typically engages the lowest gear state (which provides the highest torque) and accelerates the vehicle up to a selected speed after which the driver shifts to a higher gear. This process continues through the gear range so that the vehicle can reach its top speed. In some instances, the driver decelerates. In so doing, the driver downshifts from a higher gear to a lower gear in order to use the engine to brake the vehicle or to provide a condition of higher torque for a particular circumstance.
Transmissions are known to be of two types referred to as standard or “manual” transmissions and automatic transmissions. As is well known, a manual transmission requires a coupling of the transmission to the engine by way of a clutch assembly. A clutch assembly has an enabled state wherein the engine and the transmission are coupled and a disabled state to decouple the engine from the transmission. Typically, the driver of the vehicle depresses a clutch pedal mounted on a clutch arm or another mechanism that is, in turn, linked to the clutch assembly. The pressing of such pedal acts to move a friction plate off of the flywheel of the vehicle's engine so that the gear ratio of the transmission may be changed from one gear state to another. The actual changing of gear states is accomplished by means of a gearshift lever, as is well known. Allowing the clutch pedal to return to its normal position reengages the friction plate to the engine thereby recoupling the transmission to the engine output.
An automatic transmission, however, eliminates the use of this clutch assembly system so that the transmission changes it gear ratio in response to different load conditions on the vehicle. The automatic transmission is favored for ease and convenience by many people under normal driving conditions. Under race conditions, though, most drivers prefer to use a manual transmission. It is thought that a manual transmission gives the driver greater control over the driving conditions allowing the driver to select a desired gear ratio rather than allowing the automatic transmission to select the gear state.
The use of differing gear ratios is necessary, whether the transmission be automatic or manual, in order to prevent the turning of a particular engine at an excessive rate of revolution. Typically, an engine is known to have a “red line” over which potential damage to the engine will result should the engine's revolutions per minute exceed such limit. The gear ratios of the transmission thus allow the driver to control the revolutions of the engine for a given speed so as not to damage the engine. Thus, as the driver shifts upward in gears, the engines RPM (revolutions per minute) will remain ideally below the red line condition. Normally, this is a fairly easy matter to control during the acceleration of the engine.
When the driver is downshifting with a manual transmission, however, there is a potential for harm to the engine should the driver skip a gear. Thus, for example, should the driver be in a higher gear, such as a fourth or fifth gear, and desire to downshift into third gear. The driver accordingly depresses the clutch pedal to disengage the clutch assembly and manipulates the gearshift lever to change the gear state of the transmission. A problem may arise if the driver misses the next lower (third) gear and inadvertently shifts the transmission into a first or second gear. Since the vehicle's speed is coupled to the transmission's output and, since the transmission's output is coupled to the transmission's input through the selected gear ratio, the RPM of the transmission input may be driven by the vehicle's momentum at a rate that is excessive for the engine. More particularly, should the driver depress the clutch pedal and disengage the clutch and subsequently shift into an incorrect lower gear, the reengagement of the clutch will tend to drive the engine at an rate of revolution that is above the red line since the speed and inertia of the vehicle will now be coupled directly to the engine.
In cases where a driver miss-shifts, particularly in a racing condition, extreme damage to the engine can result from placing the vehicle in a gear range that is too low for the existing speed of the vehicle. Such damage can include the destruction of the valves, the crankshaft and other vital engine components. In effect, this damage destroys the engine preventing the vehicle from completing the race. This not only is inconvenient, but also can be quite costly due to the costs of engines in general and the very high costs of racing engines, specifically. Moreover, shifting the vehicle into a much lower gear can cause an over-braking due to the inertial mass of the engine and can create a dangerous situation and a risk of injury for the driver due to loss of control of the vehicle.
This problem has long been recognized and it is desirable to prevent engagement between the transmission and the engine during downshifting events should the proper gear range not be selected by the driver. While there have been attempts to solve this problem, there have been no known successful solutions to the Applicant. While clutch assemblies may be provided with spring loaded shift gates that are supposed to keep the driver from engaging gears that are too low for the speed of the vehicle, this approach does not work well on vehicles that are equipped with certain shift patterns and does not stop the driver from engaging the wrong gear if the driver applies enough force on the shift lever. The present invention is directed to resolving this problem and need.